import org.junit.jupiter.api.Test;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

public class test {

    @Test
    public void test1() {
        List<Integer> list = new ArrayList<>();
        list.add(1);
        list.add(2);
        list.add(3);
        Collections.addAll(list,1,2,3,4);
        System.out.println(list);
        List<Integer> list1 = list.stream().map(o -> o + 3).collect(Collectors.toList());
        System.out.println(list1);
    }

}
